Patent GB-1032133-A (GB)
Title: Automatic control system for friction welding machine
IPC: B23K20/12
Filed: 1964-08-14
Abstract: 1,032,133. Friction welding. ROCKWELL-STANDABD CORPORATION. Aug. 14, 1964 [Dec. 23. 1963], No. 33183/64. Heading B3R. An apparatus for friction welding two sections comprises means for fixedly mounting one section, means for rotatably and axially slidably mounting the other section in axially aligned abutment with the one section, means for continuously rotating the other section, including a power source, a drive means, a clutch actuable to couple the drive means to the power source and a brake acting with said drive means to stop rotation of the other section and is characterized in that there are means automatically responsive to a predetermined condition to engage the drive means, means responsive to engagement of the drive means to release the brake and engage the clutch, means responsive to the release of the brake for exerting axial force upon the other section to displace it into frictional heat generating rotational engagement with the one section until the rubbing surfaces become fusible and means automatically responsive to a second predetermined condition for releasing the clutch and applying the brake to permit the weld to form and cool. Construction of apparatus.-A bed 22 supports a fixture 26 secured to the bed and a fixture 28 slidable along the bed. Between the fixtures are two adjustable aligning and clamping assemblies 30 and 32, each having anti-friction bearings which are radially adjustable to engage the periphery of a workpiece 40, Fig. 2 (not shown), which is to be welded at each end to two further workpieces 42, 44 clamped in the fixtures 26 and 28. The workpiece 40 is rotated by an endless belt 94 which passes round the workpiece, over the pulleys 164, 178 over the guide pulleys 144, 146 and round a driving pulley 93, and is tensioned by a jockey pulley 148 operated by an hydraulic piston/cylinder assembly 383, 154. The pulleys 167, 178 are mounted on the arms 158 and 160 which between them define a recess 162 which receives the workpieee 40 in a loop of the belt 94. The arm 158 is pivoted to a frame 140, of which the arm 160 is a part, and is actuated by the piston rod 196 of an hydraulic cylinder 190. An hydraulic cylinder 212 adjusts the position of the frame 140 to align the part 40 with the parts 42, 44. The pulley 93 is driven by a motor 54 through a clutch 68 and drive shaft 76 which mounts a brake 95 and a speed-sensing device 100. The fixture 28 is moved by an hydraulic cylinder and piston assembly 226, 227 which operate a push rod 230. Coupled to the push rod 230 is a rod 242 on which are abutments 258, 258a which operate limit switches LS3, LS4, LS5, LS6. The hydraulic system comprises two pumps 310, 311, each with its own ancillaries. The pump 310 is connected to a manifold 314, the four ways of which are controlled by valves S4, S4a, S5, S6, actuated respectively by solenoids SC4, SC4a, SC5, SC6. The outlets controlled by the valves S4 and S6 are connected to opposite ends of the cylinder 226, the outlet controlled by the valve S4a is connected to a relief valve and the outlet controlled by valve S5 is connected by a line 318 to a second hydraulic cylinder 320. The piston rod 328 of this second cylinder is connected to the piston of a pneumatic cylinder 324, the pressure side of which is connected by line 368 to a series of storage tanks 370, 371, 372, 373 of varying storage and pressure capacity. The line 368 also connects via a valve S7 to a storage tank 380 which has outlets 384 and 386 controlled by a manual valve and connected to the belt tensioning cylinder 154. The tank 380 is also connected to the main air line 404. The cylinder 212 which positions the frame 140 is connected through a manually operated valve 394 to the main air line 404 via a regulator 398. The brake 95 is operated by a pneumatic cylinder 423 which is connected through a valve S2 to a storage tank 412, which in turn is connected to main line 404 via a regulator 406. The clutch 68 is operated by a motor 70 which comprises a diaphragm actuator having a push rod 444 connected to an operating lever 445. The air supply to the motor is controlled by a valve S3 in the line 438 from a storage tank 436 which is connected to the main line 404 via a regulator 430. Operation of machine.-When the machine is in the inactive condition the electric power, and hence the hydraulic power is " OFF," but the air pressure is " ON " and holds the brake 95 on and the clutch 68 disengaged. A switch 472 on the panel 344 controls the electric power and a push-button controls the hydraulic power. By pressing a " Reverse " button, full return of the piston 227 to its starting position is assured. With workpieces 40, 42 and 44 in position a " START " button is pressed and the welding cycle proceeds automatically. The arm 158 closes and thereby opens a limit switch LS1 which causes release of the brake 95 and engagement of the clutch 68. The speed sensing means 100 is activated when rotation of the shaft 76 is started. The air-pressure applied to the clutch 68 also closes a pressure switch PS2 which operates the valve S4 so that the piston 227 is displaced to the left and the heating cycle is started. As the piston 227 moves the switch LS3 is closed by the abutment 258a which starts a heating cycle timer TD3, and also opens the valve S5 connecting the manifold to the cylinder 320 so that the pressure in cylinder 226 builds up rapidly and then becomes constant. Further movement of the push rod 230 operates the switch LS4 which disengages the clutch, or alternatively the clutch may be disengaged after a time interval determined by the timer TD3. Disengagement of the clutch causes switch PS3 to operate, which through a solenoid allows air pressure to apply the brake 95 to stop the shaft. When the shaft has stopped the speed sensing means 100 operate a solenoid which opens the arm 158 and thereby operates switch LS1 which locks the brake 95 in the " ON " position and brings a second timer TD2 into circuit. This second timer causes a delay period before the final increase in axial pressure, to allow the weld to attain a desired temperature. When the timer TD2 runs out the valve S5 is moved to a second position, whereby the full accumulated high pressure from cylinder 320 is applied to cylinder 226 to forge-weld the workpieces. Simultaneously a reverse delay timer TD 1 is started which prevents reverse movement of the piston 227 and allows the weld to form and cool. When timer TD1 runs out the machine is restored automatically to the starting condition. For a workpiece of 5 sq. inches cross-sectional area the axial force during the heating cycle is 16,000 1bs., increasing to 62,000 lbs. for forging. Details are given of a complete welding cycle.